Adaptive filters are widely used for filtering signals in communication receivers. Adaptive filters are used, for example, to compensate for the response of the communication channel, to improve Signal to Noise Ratio (SNR) or to reduce Inter-Symbol Interference (ISI), to name a few examples. Various filter adaptation techniques are known in the art. Some adaptation techniques involve Least Mean Square (LMS) processes. For example, Mayyas and Aboulnasr analyze a family of LMS processes known as leaky LMS, in “Leaky LMS Algorithm: MSE Analysis for Gaussian Data,” IEEE Transactions on Signal Processing, volume 45, no. 4, April 1997, pages 927-934, which is incorporated herein by reference.
Raphaeli and Saguy investigate an adaptive equalization technique referred to as Turbo equalization, in “Linear Equalizers for Turbo Equalization—A New Optimization Criterion for Determining the Equalizer Taps,” 2nd International Symposium on Turbo Codes and Related Topics, Brest, France, Sep. 4-7, 2000, pages 371-374, which is incorporated herein by reference. Tüchler and Singer analyze equalizer performance in the Turbo equalization application, in “Minimum Mean Squared Error Equalization using A-Priori Information,” IEEE Transactions on Signal Processing, volume 50, no. 3, March, 2002, pages 673-683, which is incorporated herein by reference.
Lee et al. describe a specific class of Turbo equalization algorithms, in “Switching LMS Linear Turbo Equalization,” Proceedings of the 2004 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2004), Montreal, Canada, which is incorporated herein by reference. Yet another Turbo equalization technique is described by Choi et al., in “Adaptive Linear Turbo Equalization over Doubly Selective Channels,” IEEE Journal of Oceanic Engineering, 2011, which is incorporated herein by reference.